Instruction manual

KEW MEG seriesMODEL3144A, 3145A, 3146A, 3147A, 3148A

Compact Insulation resistance tester with 2-range

KYORITSU ELECTRICAL INSTRUMENTSWORKS,LTD.

Contents

1．Safety warnings ……………………………………………………１

2．Features ……………………………………………………………３

3．Specification ………………………………………………………４

4．Instrument layout …………………………………………………７

5．Preparation for measurement ……………………………………８5－1 Mechanical zero adjustment ………………………………８5－2 Test lead connection ………………………………………８5－3 Battery voltage check ………………………………………９5－4 Power-on-indication LED …………………………………９

6．Measurement ………………………………………………………106－1 AC voltage measurement …………………………………10

(Mains disconnection check)6－2 Insulation resistance measurement ………………………116－3 Continuous measurement …………………………………136－4 Output voltage characteristics ……………………………136－5 Backlight function …………………………………………15

7．Battery replacement ………………………………………………16

8．Notes on Housing case and accessories ………………………178－1 Case lid ……………………………………………………178－2 Neck strap and Cord case …………………………………188－3 Test prods and replacement ………………………………198－4 Adaptors for the Earth cord and replacement …………208－5 Cleaning Meter cover ……………………………………21

― 1―

１．Safety warnings

○ This instrument has been designed, manufactured and testedaccording to IEC 61010-1: Safety requirements for ElectronicMeasuring apparatus, and delivered in the best condition afterpassed the inspection. This instruction manual containswarnings and safety rules which must be observed by the userto ensure safe operation of the instrument and retain it in safecondition. Therefore, read through these operating instructionsbefore using the instrument.

WARNING¡Read through and understand the instructions contained in thismanual before using the instrument.

¡Keep the manual at hand to enable quick reference whenever necessary.

¡The instrument is to be used only in its intended applications.¡Understand and follow all the safety instructions contained inthe manual.It is essential that the above instructions are adhered to.Failureto follow the above instructions may cause injury, instrumentdamage and/or damage to equipment under test.

○ The symbol indicated on the instrument, means that the usermust refer to the related parts in the manual for safe operationof the instrument. It is essential to read the instructionswherever the symbol appears in the manual.

DANGER ：is reserved for conditions and actions that arelikely to cause serious or fatal injury.

WARNING：is reserved for conditions and actions that cancause serious or fatal injury.

CAUTION：is reserved for conditions and actions that cancause injury or instrument damage.

― 2―

DANGER¡Never make measurement on a circuit in which the electricalpotential exceeds following values.MODEL3144A/ 3147A : AC/DC600VMODEL3145A/ 3146A/ 3148A: AC/DC300V

¡Do not attempt to make measurement in the presence of flammablegasses. Otherwise, the use of the instrument may cause sparking,which can lead to an explosion.

¡Never attempt to use the instrument if it's surface or your hand are wet.¡Be careful not to short-circuit the power line with the metal part of thetest leads when measuring a voltage. It may cause personal injury.

¡Do not exceed the maximum allowable input of any measuring range.¡Never open the Battery cover during a measurement.

WARNING¡Never attempt to make any measurement if any abnormal conditions,such as a broken case or exposed metal parts are present on theinstrument and test leads.

¡Never press the Test button while connecting the test leads.¡Never rotate the Range switch with the test leads connected to theequipment under test.

¡Do not install substitute parts or make any modification to theinstrument. Return the instrument to your local KYORITSU distributorfor repair or re-calibration in case of suspected faulty operation.

¡Never touch the circuit under test during/immediately after the insulationresistance measurement. The test voltage may cause electrical shock.

¡Do not replace batteries if the instrument is wet.¡Ensure that the test leads are firmly inserted into the terminal.¡Set the Range switch to OFF position when opening the Batterycover for battery replacement.

CAUTION¡Always set the Range switch to the appropriate position beforemaking measurement.

¡Set the Range switch to "OFF" position after use and remove the testleads. The instrument consume small current at any range otherthan OFF, and it shortens the battery life. Remove the batteries if theinstrument is to be stored and will not be in use for a long period.

¡Do not expose the instrument to direct sunlight, high temperatures,humidity or dew.

¡Use a damp cloth with neutral detergent for cleaning the instrument.Do not use abrasives or solvents.

¡Do not store the instrument if it is wet. Store it after it dries.

― 3―

２．Features

MODEL3144A, 3145A, 3146A, 3147A, 3148A are two-range insulation resistance testers for testing low-voltage installation.

¡Designed to following safety standards:IEC 61010-1, IEC 61010-031, IEC 61557

¡Small and light weight.¡Auto-discharge functionWhen insulation resistance like a capacitive load is measured,electric charges stored in capacitive circuits are automaticallydischarged after measuring. Discharge can be checked with themeter.

¡Color-coded scales for easy and correct reading¡Power-on indicator on insulation resistance and battery checkranges.

¡Backlight function to facilitate working at dimly illuminatedlocation or at nighttime work.

¡AC voltage measurement functionMeasures AC voltage on all ranges without pressing the Testbutton

¡Test leads with remote control switch(voltage won't be outputted when the test lead is not connected.)

¡Robust housing case¡Neck strap for both hand's operation¡User-changeable test prod

― 4―

¡Applicable standardsIEC 61557IEC 61010-1 Measurement CAT.III 300V/ CAT.II 600V

Protection class IILocation for use: altitude 2000m or less

IEC 61010-031IEC 60529 IP40

¡Measuring range and accuracy <Insulation resistance range>

* Heavy-line circular arc on the scale indicates the primary effectivemeasuring ranges. (guaranteed accuracy range)

３．Specification

MODEL

Nominal voltageMax. effective scale valueMid-scale valueAccuracy in primary effective measuring rangesAccuracy in primary effective measuring rangesAccuracy at 0 and ∞Accuracy at no-load voltageNominal currentShort-circuit current

Response time

3144A

3147A

500V

100MΩ

2MΩ0.1～50MΩ

within ±5% of indicated value

Measuring ranges other than above, 0 and ∞.within ±10% of indicated value

within ±0.7% of scale length

0%～ +20% of nominal voltage

1mA 0%～+20%

Approx. 2mA

Meter reading comes within accuracy within 3 sec. (It may take time when measuring a capacitive load.)

250V

50MΩ

1MΩ0.05～20MΩ

125V

20MΩ

0.5MΩ0.02～10MΩ

50V

10MΩ

0.2MΩ0.01～5MΩ

100V

20MΩ

0.5MΩ0.02～10MΩ

3145A3148A 3146A 3148A

3147A

― 5―

<Number of measurement>Possible number of measurement within the "BATTERY.GOOD"range.(Measure 5 sec., and take pause for 25 sec.)

For MODEL3147A, *1: at least 800 times, *2: at least 500 times.

<Operating error>Operating error (B) is an error obtained under the nominaloperating conditions, and calculated with the intrinsic error (A),which is an error of the instrument used, and the error (En) due tovariations. According to IEC61557, the maximum operating errorshould be within +/-30%.Ｂ ＝―Ａ―＋ 1.15 × √（Ｅ12 ＋ Ｅ22 ＋ Ｅ32 ）

Ａ： Intrinsic error (%)Ｂ ： Operating error (%)Ｅ1： Variation due to changing the temperature (%)Ｅ2： Variation due to changing the Battery voltage (%)Ｅ3： Variation due to changing the position(%)

Nominal operating conditionsAmbient temperature : 0～40℃Relative humidity : 90% or lessExternal magnetic field : 400A/m or lessPosition : Horizontal～±90°Battery voltage : within "BATTERY. GOOD" range< AC voltage range>

MODELMeasured voltageAccuracy

3144A, 3147A0～600Vwithin ±3% of the max. scale value

3145A, 3146A, 3148A0～300V

50V/10MΩ100V/20MΩ125V/20MΩ250V/50MΩ500V/100MΩ

Range

0.05MΩ0.1MΩ

0.125MΩ0.25MΩ0.5MΩ

at least 1300 timesat least 1300 timesat least 1300 times*1at least 1100 timesat least 800 times*2

Possible number of measurement

Resistor for test

― 6―

Temperature & humidity : 0℃～40℃ (RH: 85% or less)range (no condensation)Storage temperature & : -20℃～＋60℃ (RH: 75% or less)humidity range (no condensation)Insulation resistance : at least 50MΩ/ DC500V between

the electrical circuit and the enclosureWithstand voltage : AC3700V(50/60Hz) for 1 min. between

the electrical circuit and the enclosure Overload protectionInsulation resistance range:50V/ 100V/ 125V/ 250V 300V (50/60Hz) for 10 sec.500V 600V (50/60Hz) for 10 sec.AC voltage range:Max. measured voltage x 1.2 (50/60Hz) for 10 sec.

Dimension : approx. 90(L) x 137(W) x 40(D)mmWeight : approx. 340g (including batteries)Power source : R6P (SUM-3), AA, x 4pcsNominal power : 1.8VA

AccessoriesMODEL7139 Test lead with remote control switch 1 setMODEL7101 Flat test bar 1 pceMODEL7131 Safety alligator clip 1 pceMODEL8017 Extension prod 1 pceNeck strap 1 pceCord case 1 pceR6P (SUM-3), size AA 4 pcsInstruction manual 1 pce

OptionalMODEL7115 Extension probeMODEL8016 Pickle type prod

Pickle type prod

Extension probe

― 7―

①Meter zero adjuster ②Test button③Scale plate ④Pointer⑤Insulation resistance scale ⑥AC voltage scale⑦"BATTERY-GOOD" range ⑧Power-on-indication LED⑨Probe socket ⑩Backlight switch⑪Range switch⑫Test lead with remote control switch (MODEL7139)⑬Remote control switch ⑭Line probe⑮Earth cord ⑯Standard prod (MODEL8072)⑰Probe connector ⑱Flat test bar (MODEL7101)⑲Safety alligator clip ⑳Extension prod (MODEL7131) (MODEL8017)

４．Instrument layout

Fig. 1 Instrument layout

― 8―

5－1 Mechanical zero adjustment

With the Range switch set to the OFF position and withoutpressing the Test button, turn the Zero adjuster with ascrewdriver so that the pointer lines up with the "∞" mark on aninsulation resistance scale. In case the instrument is used at thesloping place, ensure that the pointer lines up with the "∞" marktilting the instrument to the necessary angle.

5－2 Test lead connection

Insert the Probe connector into the Probe socket on theinstrument correctly as shown below.

５．Preparation for measurement

DANGERWhen the Test button or the Remote control switch is pressedwith the Range switch set to an insulation resistance range,take care not to touch the tip of the Test probe where a highvoltage is present in order to avoid possible shock hazard.

― 9―

CAUTIONInstrument doesn't operate without connecting the test leadeven if the Test button is pressed down. Battery check andoperation check are not available without connecting the testlead. The Backlight function is available at any time.

5－3 Battery voltage check(1) Connect the test lead to the instrument, and set the Rangeswitch to the BATT. CHECK position.

(2) Press the Test button or Remote control switch.(3) If the meter pointer does not move to BATT GOOD, replacethe batteries as shown in Section 7 "Battery replacement".

CAUTIONNever keep the Test button pressed or locked during batterycheck to avoid battery power drain.

5－4 Power-on-indication LEDOn an insulation resistance range or BATT. CHECK range,when the Test button or Remote control switch is pressed, thepower-on-indication LED (red) l ights up, indicating theinstrument is in the operation mode.

Batteries have exhausted.Replace the batteries.

Proceed to measurement.

― 10 ―

6－1 AC voltage measurement (Mains disconnection check)The AC voltage measurement function is available on any ranges.(1) Connect the Earth probe to the earth of the circuit under testand Line probe to the other side. If the circuit is not earthed,connect Earth probe to any appropriate conductor.

(2) Without pressing the Test button or Remote control switch,take the reading on the AC voltage scale.

６．Measurement

CAUTION Never press test button

CAUTION Never press remote switch

AC voltage measurement (Mains disconnection check)The AC voltage measurement function is available on any ranges.

DANGER¡Never make measurement on a circuit in which the electricalpotential exceeds the voltage measuring range in order toavoid possible shock hazard. (Refer to Section 3."Specification, AC voltage measurement.)

¡When testing installation that has a large current capacity,such as a power line, be sure to make measurement on thesecondary side of a circuit breaker in order to avoid personalinjury.

¡Do not press the Test button or Remote control switch duringvoltage measurement.

¡Never short live conductors with the tip of a probe to avoidpersonal injury.

¡Do not make measurement with the Battery cover removed.

― 11 ―

<Simplified measurement of DC voltage>This instrument also provides simplified measurement of DCvoltage. Multiplying 0.9 by the indicated value at AC voltage scaleprovides the DC voltage value. However, the polarity isn't indicated.DC voltage (V) = Indicated value at AC voltage scale x 0.9 (V)

6－2 Insulation resistance measurementBefore performing any insulation test, check the maximum voltage that may be applied to the circuit under test.

Note:¡Some circuits have an unstable insulation resistance, whichcauses the reading to vary during measurement.

¡The instrument may generate a high pitch tone duringmeasurement. This is not a failure.

¡If the circuit under test has a large capacitive load, it may takesome time before the final reading can be obtained.

¡On insulation resistance range, DC voltage is supplied throughEarth and Line probes, with Earth probe having positive polarity.Earth probe should be connected to the earth conductor in thecircuit under test. Such connection is known to be more suitablefor insulation tests since an insulation resistance value measuredwith the positive side connected to earth is typically less than thattaken through the reversed connection.

DANGER¡When the Test button or Remote control switch is pressedwith the Range switch set to an insulation resistance rangeposition, take care not to touch the tip of the test probe or thecircuit under test where a high voltage is present in order toavoid possible shock hazard.

¡Do not make measurement with the Battery cover removed.

CAUTIONEnsure that the circuit under test is de-energized prior to anyinsulation testing.

― 12 ―

(1) Check the maximum voltage that may be applied to the circuitunder test. Set the Range switch to a desired insulationresistance range.

(2) Connect Earth probe to the earth terminal of the circuit undertest. If the circuit is not earthed, connect Earth probe to anyappropriate conductor.

(3) Connect Line probe to the circuit under test and press the Testbutton or Remote control switch.

(4) Take the reading on the scale for the selected insulationresistance range.

Load side

Circuit breaker

Remote control switch

Press the test button or remote control switch.

Select range

Test button

Connect side Earth terminal

source side

CAUTION Make sure to furn off the circuit breaker.

(5) Release the Test button or Remote control switch and leavethe probes connected to the circuit under test to dischargecharges stored in the capacitance of the circuit.

DANGER¡Do not touch the circuit under test immediately after testing.Charges stored in the capacitance of the circuit may causeelectrical shock.

¡Leave the probes connected to the circuit under test until thepointer returns to the left end of the scale. Never touch thecircuit before the discharging completes.

― 13 ―

<Auto discharge function>This function allows electric charges stored in the capacitance ofthe circuit under test to be automatically discharged aftertesting.Discharge can be monitored by the AC voltage reading.

(6) Set the Range switch to the OFF position, and disconnect theprobes from the instrument.

6－3 Continuous measurementFor continuous measurement, a lock-down feature isincorporated on the Test button. Pressing and turning clockwiselocks the button in the operating position, the button is releasedby turning it counterclockwise.

Nominal voltage0.05MΩ

50V0.1MΩ

100V0.125MΩ

125V0.25MΩ

250V0.5MΩ

500VLower limit of insulationresistance to supplynominal current (1mA)

DANGERWhile the Test button is locked down, a high voltage is presentat the tip of a probe. Attention should be paid to avoid possibleshock hazard.

6－4 Output voltage characteristicsThis instrument conforms to IEC61557. This standard definesthat the nominal current shall be at least 1mA, and the lowerlimit of the insulation resistance maintaining the nominal voltageat the measurement terminal. (See the graph below.)This value is calculated by dividing the nominal voltage bynominal current. i.e., in case that the nominal voltage is 500V,the lower limit of the insulation resistance is found as follows. Divide 500V by 1mA equals 0.5MΩThat is, insulation resistance of 0.5MΩ or more is requiredtoprovide the nominal voltage to the instrument.

― 14 ―

M-3144A Output characterisstics

M-3145A Output characterisstics

M-3146A Output characterisstics

Insulation resistance

Insulation resistance

Insulation resistance

Output voltage(V)

Output voltage(V)

Output voltage(V)

Note) For the output characteristicsof M3147A,see the left graphfor.M3144A(at 500V)and 3145A(at125V).

Note) For the output characteristicsof M3148A,see the left graphfor.M3145A.

― 15 ―

6－5 Backlight functionTo facilitate working in dimly lit situations, a backlight function isprovided which illuminates the scale plate. Press the backlightswitch to operate this function. The backlight will light up forabout 60 sec., and then turned off automatically.

― 16 ―

DANGERNever open the Battery cover during a measurement.

WARNINGTo avoid possible electric shock, remove test leads beforeopening the Battery cover. After replacing batteries, be sureto tighten up the screws for Battery cover.

CAUTIONDo not mix new and old batteries.Install batteries in correct polarity as marked inside the Battery compartment.

(1) Set the Range switch to "OFF" position, and remove the testleads from the instrument.

(2) Loosen the Battery-cover-fixing screws, and remove the Batterycover. Always replace all 4 batteries with new one at the sametime.

(3) After replacing batteries, be sure to tighten up the screws forBattery cover.

7．Battery replacement

Battery-cover-fixing-screws

Install batteries in correct polarityas marked inside the Batterycompartment.

― 17 ―

8－1 Case lidCase lid can be fit under the Housing case while makingmeasurement.

(1) Unhook and open the Case lid.(2) Turn it 180 degrees.(3) Put the Case lid under the Housing case.(4) Hook it on to the Housing case.

8．Notes on Housing case and accessories

― 18 ―

8－2 Neck strap and Cord caseThis instrument is equipped with a strap to suspend from theneck to allow both hands to be used freely for easy and safeoperation.

(1) How to fix the belt

How to install the Cord case

How to install the Neck strap

Neck strap

Belt ring

Hook

Pull up the belt.

― 19 ―

Female 　Screw

Male Screw

Prod

Pickel Prod

Extension Prod

Hexagonal Hole

8－3 Test prods and replacement

1. Types of Test prodsMODEL8072:Standard Test prod

Used for ordinary measurement.(Attached to the Line probe at the time ofpurchase.)

MODEL8017:Extension probeUsed in difficult-to-reach situations.

MODEL8016:Pickle prod (Optional)Used to hook the probe on a conductor.

2. How to replace Test prodTo remove the Test prod, turn the cap of LINE probecounterclockwise. Insert the threaded end of another prodinto the hexagonal hole on the probe cap as shown. Then,turn the probe cap clockwise to secure it on the body of theprobe.

― 20 ―

8－4 Adaptors for the Earth cord and replacement

1. AdaptorsMODEL7131:Safety alligator clip

Connected to the Earth terminal of the Earthterminal board.

MODEL7101:Flat test barConnected to the earth side of the outlet.

2. How to replace AdaptorsTo remove the adaptors, pull them out. Then firmly attach theadaptor as desired to the tip of the Earth cord.

Safety alligator clip

Flat test bar

― 21 ―

8－5 Cleaning Meter cover

This instrument is managed by our company's quality standardand is delivered in the best condition after passed theinspection. But in the dry time of winter static electricitysometimes builds up on the meter cover due to thecharacteristic of plastic.When static builds up on the meter cover and affects the meterreading, use a cloth damped with off-the-shelf anti-static agentor detergent to wipe the meter cover surface.

CAUTION¡When the pointer deflects by touching the surface of thisinstrument or zero adjustment cannot be made, do not try tomake measurement.

¡Antistatic agent has been applied to the meter cover of theinstrument for electrification prevention, therefore, do not rub itstrongly with a dry cloth etc. even if it is dirty.

¡To avoid possible deforming or discoloring, do not usesolvents.

DISTRIBUTOR

KYORITSU ELECTRICALINSTRUMENTSWORKS, LTD.No.5-20, Nakane 2－chome,Meguro-ku,Tokyo, 152-0031 JapanPhone:81－3－3723－0130 Fax:81－3－3723－0152URL:http://www.kew-ltd.co.jpE-mail:info@kew-ltd.co.jpFactories:Uwajima & Ehime

04-08 92-1648